#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
    float ball = 100;
    int n;
    scanf("%d", &n);
    float num = ball;
    for (int i = 1; i < n; i++)
    {
        num += ball;
        ball = ball / 2;
    }
    printf("%.4f", num);
    return 0;
}